Electrolysis control system for boats



' Dec. 23, 1969 A. R. BOOKER 3,485,741

ELECTROLYSIS CONTROL SYSTEM FOR BOATS Filed Dec. 12, 1966 7 FIG. 2.

BY HA5 A 7'7'0ENE Y5 HARE/5 mac/1, Russia-u. a KERN United States Patent Office Patented Dec. 23, 1969 3,485,741 ELECTROLYSIS CONTROL SYSTEM FOR BOATS Aylwin R. Booker, 4887 Palo Drive, Tarzana, Calif. 91356 Filed Dec. 12, 1966, Ser. No. 600,827 Int. Cl. C231? 13/00 US. Cl. 204197 6 Claims ABSTRACT OF THE DISCLOSURE An electrolysis control system for protecting metal members in a boat and including an insulating plate, a current conductive member on a face of the insulating plate, a sacrificial metal plate carried on a lower portion of the insulating plate over and in electrical contact with the current conductive member, and a connector for supporting the sacrificial plate below the water line outside the boat and making an electrical connection through the hull of the boat above the water line.

The present invention relates to improvements in electrolysis control systems and apparatus and, more particularly, to a novel system for preventing electrolytic destruction of metal members which extend through the hull of a boat.

Electrolytic destruction of metals is a well-known and understood reaction and occurs when dissimilar metals are connected together and submerged in a liquid bath to form an electrolytic cell. As current flows in the cell, the member formed of the least noble metal is literally eaten away and destroyed. In a boat, such electrolytic destruction occurs when dissimilar metal fittings and the like extend through the hull of the boat and contact the water.

To reduce electrolytic destruction of fittings and other through-hull metal members, it is presently common practice to connect a zinc plate to the side of the boat below the water line using a bronze or stainless steel bolt. Within the boat, a bonding wire connects the bolt to the metal members which extend through the hull to thereby form an electrolysis control system. Since zinc is very high on the electromotive force series and is less noble than steel, copper and stainless steel, current flows from the metal members through the bonding wire to the zinc plate and the zinc plate is eaten away and sacrified to the protection of the metal members.

Unfortunately, while the conventional electrolysis control system is functioning to protect the metal members, serious electrolytic corrosion or burning is produced in the section of the hull around the bolt and behind the sacrificial zinc plate. This is a particularly acute problem in wooden hull boats wherein the electrolytic current flowing through the salt water saturated wood creates a burning action in the wood turning it to pulp and thus destroying planking in the hull of the boat.

In some instances, the problems of burning have become so serious that the conventional electrolysis control system has been replaced in favor of attaching separate zinc plates or collars to the through-hull metal members. Unfortunately, this approach is not feasible for all through-hull fitting and requires periodic inspection of each through-hull member. This means that the throughhull members must be periodically removed or that a diver be employed to perform the same inspection operation. Both methods are time consuming and expensive, particularly when difficult to reach or remove parts are involved.

Another shortcoming of the conventional electrolysis system is that the electrolytic action between the dissimilar metal members may override the action of the zinc plate when the area of the zinc plate becomes small. Under such conditions, it is possible for steel fittings to be sacrificed by reacting with copper fittings, for copper fittings to be sacrificed by reacting with stainless steel fittings, and steel fittings to be sacrificed by reacting with stainless steel fittings.

In view of the foregoing problems and shortcomings of conventional electrolysis control systems, it is an object of the present invention to provide an improved electrolysis control system and a method of installing the system in a boat which permits the system to protect through-hull metal members from electrolytic destruction without producing electrolytic corrosion or burning of the hull of the boat.

Another object of the present invention is to provide an improved electrolysis control system for boats, including an insulation-surrounded connector extending through the hull of a boat above its water line to support a sacrificial metal plate below the water line and to electrically connect through-hull metal members within the boat to the sacrificial metal plate, whereby current fiowing from the metal members to the sacrificial metal plate passes through an electrically insulated and substantially waterfree portion of the hull and does not produce electrolytic corrosion and burning of the hull around the connector.

A further object of the present invention is to provide an improved electrolysis control system for a boat, wherein electrolytic action between dissimilar metal members in the boat is prevented and therefore cannot override the action of a sacrificial metal plate, regardless of the size of the sacrificial metal plate.

Still another object of the present invention is to provide an improved electrolysis control system for a boat, including an electrical circuit which permits only unidirectional current flow from different type metal throughhull members to a sacrificial metal plate connected to the outside of the boat, thereby preventing electrolytic action between the dissimilar metal members which might otherwise override the action of the sacrificial metal plate and cause undesired electrolytic destruction of the less noble metal members.

A still further object of the present invention is to provide a novel connector including an insulated bolt for extending through a hole in the side of a boat to connect a sacrificial metal plate to through-hull metal members in the boat and to thereby electrically insulate electrolytic current flowing through the hull of the boat from the hull and thus prevent electrolytic corrosion or burning of the hull around the connector.

Another object of the present invention is to provide a novel mounting plate for a sacrificial metal plate in a boats electrolysis control system, the plate having a backing of insulating material for protecting the side of the boat from electrolytic corrosion or burning, and a current conductive forward face for electrical connection to the sacrificial metal plate, and the mounting plate being adapted for above-water connection to the side of the boat with a lower portion carrying the sacrificial metal plate below the water within easy reach for inspection and replacement.

A foregoing as well as other objects and advantages of the present invention may be more clearly understood by reference to the following detailed description when considered with the drawing which, by way of example, illustrates one form of electrolysis control system including the features of the present invention.

In the drawing:

FIG. 1 is a combination sectional and diagrammatic representation of one form of the electrolysis control system of the present invention, including a sacrificial metal plate on a mounting plate, an insulated connector secured to the mounting plate and extending through a hole to a side of a boat above the water line to support the sacrificial metal plate below the water, and circuit means between the insulated connector and dissimilar metal through-hull members in the boat;

FIG. 2 is a schematic representation of the circuit means diagrammatically illustrated in FIG. 1; and

FIG. 3 is a front view of the mounting plate of FIG. 1 with the sacrificial metal plate removed.

In the drawing, the electrolysis control system is represented by the numeral and comprises a mounting plate 12, a sacrificial metal plate 14, an above-water, through-hull connector 18 and circuitry 20. Generally speaking, the mounting plate 12 is designed to support and electrically insulate the sacrificial metal plate 14 from a side 16 of a boat (not shown) while electrically connecting the sacrificial metal plate to the through-hull connector 18. Within the boat, the circuitry electrically connects dissimilar metal through-hull members to the connector 18 and hence to the sacrificial metal plate 14.

The sacrificial metal plate 14 is formed of a metal such as zinc which is high in the electromotive force series and'less noble than the metals forming the throughhull members in the boat. Accordingly, after the electrolysis control system has been installed in a boat, current flows from the dissimilar metal members through the circuitry 20 and connector 18, and to the sacrificial metal plate 14 via the mounting plate 12. As this occurs, the sacrificial metal plate 14 is literally eaten away and sacrificed to the protection of the metal members.

During operation of the system 10, the mounting plate 12 electrically insulates the sacrifiicial metal plate 14 from the side of the boat to prevent electrolytic corrosion of the hull behind the sacrificial plate.

The through-hull connector 18 is designed to electrically insulate the current flowing therethrough from the hull of the boat and thereby prevents electrolytic corrosion or burning of the hull around the connector.

The circuitry 20 is designed to permit only unidirectional current flow from the metal members to the connector 18 and thereby prevents electrolytic action between dissimilar metal members in the boat which might otherwise override the action of the sacrificial metal plate 14 and cause undesired electrolytic destruction of the less noble metal members.

More particularly, the mounting plate 12 comprises an insulating backing plate 22 of a dielectric material having a layer 24 of a current conductive material, such as copper, bonded or laminated to a front face of the insulating plate. The layer 24 does not completely cover the front of the insulating plate 22. Rather, it is preferably of the shape or surface pattern illustrated in FIG. 3 formed by chemical etching the layer after lamination on a forward face of the insulating plate. The layer 24, accordingly, includes a rectangular lower portion 26 and inwardly converging arm portions 28 and 30 extending upwardly from the lower portion to a circular upper junction 32.

Four holes 34 extend through the insulating plate 24 adjacent the four corners of the rectangular portion 26 of the layer 24 and are adapted to receive four screw 36 for connecting the mounting plate 12 to the side 16 of the boat. In this regard, it should be noted that the screws 36 connect mounting plate 12 to the side of the boat such that the lower portion thereof, including the lower portion 26 of the layer 24, extends below a water line 38 for the boat, while an upper portion of the mounting plate, including the arms 28 and 30 and the junction 32 of the layer, extend above the water line. By definition, the water line 38 is a mark or imaginary line on the hull of the 'boat corresponding to the top surface of the water along the hull when the boat is afloat on an even keel.

In addition to the holes 34, a hole 40 extends through an upper portion of the mounting pl te 2 a d thro gh the circular junction 32 in the layer 24, and a pair of holes 42 extend through a lower portion of the mounting plate and through the lower portion 26 of the layer 24. The hole 40 is adapted to receive one end of the through-hull connector 18 while the holes 42 are adapted to receive metal bolts 44.

The heads of the bolts 44 bear against the front of the sacrificial metal plate 14 while the shanks of the bolts extend through holes 45 in the sacrificial plate and through the holes 42 to each receive a nut 46. The nuts 46 bear against the back of the mounting plate 14 to tightly secure the sacrificial metal plate 14 over and in electrical contact with the rectangular lower portion 26 of the layer 24. Accordingly, when the mounting plate 12 is secured to the side of the boat as illustrated in FIG. 1, the sacrificial metal plate 14 extends below the water line 38 and is completely inmmersed in water to act as a sacrificial electrode in the electrolytic cell arrangement of the system 10. Being mounted just below the water line 38, the sacrificial metal plate 14 is within easy reach for periodic visual inspection and for simple replacement as necessary.

The through-hull connector 18 is illustrated most clearly in FIG. 1 and comprises a metal sleeve 48, preferably formed of bronze or stainless steel, and a solid metal bolt 50, preferably of copper. The sleeve 48 is adapted to axially receive the bolt 50 with threaded end portions of the bolt extending beyond opposite ends of the sleeve. An insulator 52 fills the void between the bolt and the sleeve and firmly locks the sleeve on the bolt to form a solid unit for fitting into and through a predrilled hole 54 in the side 16 of the boat above the water line 38. Ends 56 and 58 of the sleeve are threaded and receive nuts 60 and 62 for bearing against opposite surfaces of the side 16 to firmly lock the sleeve and bolt combination within the hole 54.

Thus positioned, the end of the bolt 50 outside the boat extends through the hole 40 in the mounting plate 12 and receives a metal washer 64 and nut 66 to tightly secure the mounting plate to the through-hull connector 18. The metal washer tightly engages the junction 32 of current conductive layer 24 to electrically connect the conductive layer to the bolt 50 through the nut 66. Accordingly, the sacrificial metal plate 14 is likewise electri'cally connected to the bolt 50.

The end of the bolt 50 within the boat is electrically connected to the circuitry 20 and hence to dissimilar metal through-hull members in the boat. In this regard,

- an insulating washer 68 of dielectric material extends around the end of the bolt 50 and bears against the sleeve 48. One end of an electrical lead 70 extends around the bolt 50 between the insulating washer 68 and a metal washer 72 and is tightly secured to the bolt by a nut 74.

Thus connected, current flows from the various metal members in the boat through the circuitry 20, the lead 70, the bolt 50, and hence through the side 16 of the boat above the water line 38 to the conductive layer 24 onthe forward face of the mounting plate 12. From the conductive layer, the current flows directly to the submerged sacrificial metal plate 14. As this occurs, the sacrificial metal plate is literally eaten away and destroyed to the protection of the metal members in the boat.

Since the current flows through a substantially waterfree portion of the hull of the boat above the water line 38, problems of electrolytic corrosion and burning of the hull of the boat around the connector are substantially reduced. Moreover, the insulator 52 electrically insulates the current carrying bolt 50 from the hull of the boat to further reduce any possible electrolytic corrosion or burning. Furthermore, even if the insulation 52 should break down and permit some current to leak toward the hull, the metal sleeve 48 functions to distribute the current and to prevent it from reaching a density sufficicnt to produce a burning of the hull, even it formed of a wooden material. Accordingly, the through-hull connector 18 effectively reduces any possibility of electrolytic corrosion or burning of the hull around the connector.

Similarly, the insulating plate 24 insulates the sacrificial metal plate 14 from the metal sleeve 48 and from the side 16 of the boat and thus prevents electrolytic corrosion of the side of the boat behind the sacrificial metal plate.

As previously indicated, one problem of conventional electrolysis control systems is that electrolytic action between dissimilar metal members connected in the system may be sufficient to override the action of the sacrificial metal plate, particularly when the plate has been reduced to a relatively small size. When this occurs, the least noble of the metal members in the boat is subject to electrolytic destruction. In the present invention, the circuitry 20 prevents such occurrences by allowing only unidirectional current flow from the metal members in the boat to the sacrificial metal plate 14. In this manner, the circuitry 20 prevents electrolytic action'between the dissimilar metal members in the boat which might otherwise override the action of the sacrificial metal plate.

To accomplish this, the circuitry 20 Preferablyincludes a first terminal 76 for connection to the lead 70, and a plurality of second terminals 78, 80 and 82 for separate connection to metal members of difierent type in the boat. For example, terminal 78 is connected to all bronze through-hull members, terminal 80' is connected to all stainless steel members, and terminal 82 is connected to all steel members. Diodes 84, 86 and 88 are connected in parallel between the terminals 78, 80 and 82 respectively and the terminal 76. The anodes of the diodes are connected to the terminals 78, 80 and 82 and the cathodes to the terminal 76. Therefore, current flows from the ter minals 78, 80 and 82 to the terminal 76 and hence to the sacrificial metal plate 14 and current is prevented from flowing between the terminals 78, 80 and 82 and hence to the metal members connected thereto. In this manner, the diodes prevent electrolytic action between the dilferent type metal members despite the fact that the sacrificial metal plate 14 may have been completely destroyed.

Accordingly, not only does the electrolysis control system of the present invention provide protection for through-hull metal members without producing electrolytic corrosion or burning of the hull of the boat, but it also prevents electrolytic action between dilferent type metal members which might otherwise override the action of the sacrificial metal plate and result in undesired electrolytic destruction of the lesser noble metal members. This, the present invention accomplishes with a novel through-hull connector 18 which electrically insulates a through-hull bolt from the hull of the boat and by circuitry which permits only unidirectional current from the metal members to the sacrificial metal plate.

The mounting plate 12 also plays an important role in the over-all operation of the system 10 by electrically insulating the sacrificial plate 14 from the side of the boat and by allowing the sacrificial plate to be submerged in water while electrically connected by the through-hull connector 18 through the hull of the boat above the water line 38 to reduce possible electrolytic corrosion or burning of the hull.

The mounting plate 12 also simplifies the installation of the system 10 in the boat. In particular, to install the electrolysis control system, the sacrificial metal plate 14 is first connected to the lower portion of the mounting plate 12 with the bolts 44 and nuts 46. Then, using the mounting plate 12 as a template, the hole 54 is bored through the side 16 of the boat immediately above the water line 38. Next, the through-hull connector 18 is inserted through the hole 54 and secured in place by the nuts 60 and 62. The mounting plate 12 then is located on the outer end of the bolt 50 through the hole 40 and secured to the side 16 of the boat by the screws 36. Next, the conductive layer 24 is electrically connected to the bolt 50 using the washer 64 and nut 66. Finally, the different type metal members in the boat are connected to the inner end of the bolt 44 by the circuitry 20 and the lead 70 to complete the system 10.

The foregoing method of installation is extremely rapid and permits the sacrificial metal plate 14 to be located immediately below the water line within easy reach for quick inspection and replacement without requiring removal of the other components in the electrolysis control system.

While a particular form of electrolysis control system has been described in some detail herein, changes and modifications may be made in the illustrated form without departing from the spirit of the invention. It is therefore intended that the present invention be limited in scope only by the terms of the following claims.

Ixclaim:

1. An electrolysis control system for protecting metal members in a boat having a predetermined water line when afloat on an even keel, said system comprising:

an insulating plate of a dielectric material;

a current conductive means on a forward face of said insulating plate;

a sacrificial plate of a metal less noble than said metal members on a lower portion of said insulating plate over and in electrical contact with said current conducting means; and

connector means including first means extending through a predrilled hole in a side of said boat above said water line and through a hole in an upper portion of said insulating plate for supporting said lower portion and said sacrificial plate below said water line outside said boat, second means outside said boat for securing said insulating plate on said first means and for electrically connecting said current conducting means to said first means, and third means inside said boat for electrically connecting said first means to said metal members.

2, The system of claim 1 wherein said third means in cludes electrical circuit means in said boat including a first terminal for connecting to said first means, a plurality of second terminals for connecting to members of different type metal in said boat, and diode means between said first terminal and each of said second terminals, said diode means being poled for current flow from said second terminals to said first terminal.

3. An electrolysis control system for protecting metal members in a boat having a predetermined water line when afioat on an even keel, said system comprising:

an insulating plate of a dielectric material;

a current conducting means on a forward face of said insulating plate;

a sacrificial plate of a metal less noble than said metal members;

first connector means for securing said sacrificial plate to a lower portion of said insulating plate over and in electrical contact with said current conducting means;

second connector means electrically connected to said current conducting means and extending through a predrilled hole in a side of said boat above said water line for supporting said insulating plate at said side of said boat with said lower portion and said sacrificial plate below said water line and fore defining a current path between the inside of said boat and said current conducting means; and

third connector means for electrically connecting said metal members to said second connector means inside said boat.

4. The system of claim 3 wherein said second connector means comprises:

a metal bolt extending through said predrilled hole;

electrical insulation around and secured to said bolt in said hole;

means for securing said bolt in said hole; and

means for securing said insulating plate on and electrically connecting said current conducting means to an end of said bolt outside said boat,

5. A system of claim 4 wherein said second connector means further includes a metal sleeve around and secured to said insulation in said hole, and wherein said means for securing said bolt in said hole includes means on said sleeve for bearing against opposite surfaces of said side of said boat around said hole.

6. An electrolysis control system for protecting metal members in a boat having a predetermined water line when afloat on an even keel, said system comprising:

an insulating plate of dielectric materials;

a layer of current conductive material on a forward face of said insulating plate;

a sacrificial plate of a metal less noble than said metal members;

first connector means for connecting said sacrificial plate to a lower portion of said insulating plate over and in electrical contact with said layer;

second connector means for extending through a predrilled hole in a side of said boat above said water line and for connecting said insulating plate to said side of said boat with said lower portion extending below said water line, said second connector means including a metal sleeve with threaded end portions for fitting into and extending through said hole, a metal bolt extending through said sleeve with threaded end portions extending therebeyond, an insulator around said bolt and insulating said sleeve from and securing said sleeve on said bolt, first and second nuts for threadedly engaging said threaded end portions of said sleeve to bear against opposite surfaces of the side of said boat around said hole to secure said sleeve and bolt in-said hole, a third nut for threadedly engaging one of said threaded end portions of said bolt to bear against said conductive layer around a hole in an upper portion of said layer and insulating plate to thereby secure said insulating plate on said bolt and to electrically connect said sacrificial plate to said threaded end of said bolt within said boat, and a fourth nut for threadedly engaging said end of said bolt in said boat to secure an electrical lead thereto; and

electrical circuit means including a first terminal for connecting to said electrical lead, a plurality of second terminals for connection to members of different type metal in said boat, and diode means between said first. and each of said second terminals, said diode means being poled for current flow from said second terminals to said first terminal.

References Cited UNITED STATES PATENTS 9/1959 Sabins 204-197 10/1959 Sabins 204-l97 OTHER REFERENCES Reprint from Corrosion, vol. 6, No. 7, pp. 216-224, July 1950, Dow Chemical 00., pp. 1-9. 

